1. Field of the Invention
The present invention relates to processing interlaced video data to generate a deinterlaced output, and more particularly, to a method and apparatus of processing interlaced video data to generate each output frame corresponding to an interlaced field through blending deinterlaced frames.
2. Description of the Prior Art
In conventional interlaced scanning, an odd field composed of pixels located in odd scan lines and an even field composed of pixels located in even scan lines are successively scanned and generated. Recently, progressive scan technique, which is also referred to as non-interlaced scan, generates frames for the odd field and the even field respectively and then scans the frames using double scan frequency in sequence to display the video contents on a display screen. In this way, the quality of the displayed image can be improved greatly. In order to display video data in progressive scan, a deinterlacing operation for converting an interlacedly scanned video input into a sequentially (progressively) scanned video output is required. Specifically, the deinterlacing operation is configured to interpolate a new scan line between two successive scan lines within a field.
Nowadays, the deinterlacing technique becomes more and more important due to the popularity of LCD apparatuses, such as LCD monitors and televisions. In general, the conventional analog television signal, complying with NTSC standard or PAL standard, carries an interlaced content, whereas the video displayed on the LCD apparatuses is a progressive content. Therefore, the deinterlacing technique is commonly employed by an LCD apparatus to convert interlaced fields into deinterlaced frames. Please refer to FIG. 1. FIG. 1 is a diagram illustrating a conventional deinterlacing operation. As shown in FIG. 1, an interlaced field FI(n−1) is an even field (also called bottom field) including pixels located in even scan lines L2, L4, L6, L8, L10 of an original frame FR_I(n−1), and an interlaced field FI(n) immediately following the interlaced field FI(n−1) is an odd field (also called top field) including pixels located in odd scan lines L1, L3, L5, L7, L9 of an original frame FR_I(n) immediately following the original frame FR_I(n−1) in time domain. For example, the original frames FR_I(n−1) and FR_I(n) could be obtained from capturing a scene using an image capturing device. As shown in FIG. 1, the original frames FR_I(n−1) and FR_I(n) are derived from capturing a still scene. Therefore, original frames FR_I(n−1) and FR_I(n) have the same image content.
After the interlaced video data, including the interlaced fields FI(n−1) and FI(n), are transmitted from a source end (e.g., a TV service provider) to a receiver end (e.g., a television), a deinterlacer 102 is implemented to generate deinterlaced frames through processing the incoming interlaced video data according to a specific deinterlacing technique. For example, the deinterlacer 102 adopts an edge-adaptive deinterlacing technique to generate a deinterlaced frame FR_D(n−1) corresponding to the interlaced field FI(n−1) that is extracted from the received interlaced video data, and a deinterlaced frame FR_D(n) corresponding to the interlaced field FI(n) that is extracted from the received interlaced video data.
Regarding the video deinterlacing applied to the odd fields and even fields, the missed scan lines (e.g., odd scan lines missing in the even field, or even scan lines missing in the odd field) are generated according to the pixels located in the neighboring scan lines and estimated edge directions. However, under certain circumstances, a simple edge-adaptive deinterlacing fails to correctly estimate the edge direction. As shown in FIG. 1, the deinterlaced frames FR_D(n−1) and FR_D(n), compared with the original frames FR_I(n−1) and FR_l(n) respectively, contain distorted images. Therefore, the pixel value at a certain position of a current deinterlaced frame, which is a deinterlaced output frame, may be significantly different from that at the same position in the adjacent deinterlaced frame (i.e., a previous deinterlaced frame or a next deinterlaced frame). As the human eyes are sensitive to temporal flickers due to temporal difference, the video quality of the deinterlaced output is degraded due to serious flickers perceived by the user.
Therefore, a method and related apparatus which can efficiently eliminate or alleviate flickers between two deinterlaced frames successively displayed on a display screen are highly demanded.